From the Early Triassic Wordie Creek Formation of East Greenland

Remains of Saurichthys (Pisces, Actinopterygii) from the Early Triassic Wordie Creek Formation of East Greenland

ILJA KOGAN

Kogan, I. 2011. Remains of Saurichthys (Pisces, Actinopterygii) from the Early Triassic Wordie Creek Formation of East Greenland © 2011 by Bulletin of the Geological Society of Denmark, Vol. 59, pp. 93–100. ISSN 0011–6297. (www.2dgf.dk/publikationer/bulletin) https://doi.org/10.37570/bgsd-2011-59-09

Previously undescribed specimens of Saurichthys from the basal part of the Early Triassic Wordie Creek Formation (Griesbachian) of East Greenland demonstrate a remarkably complete squamation especially in the anterior trunk portion. Scales of the mid-lateral row are high and those of the mid- dorsal and mid-ventral rows broad and conspicuous by having a pronounced longitudinal keel on their inner surface; additional dorso-lateral and ventro-lateral scale rows are present. This pattern resembles that of Saurichthys dayi from the Early Triassic of Alberta and British Columbia. Differences in fin morphology suggest, however, that the Greenland form is probably not conspecific. A second Early Triassic species of Saurichthys occurring in East Greenland probably comes from a higher stratigraphic level (late Griesbachian to early Dienerian) with a different ichthyofaunal composition. Received 28 July 2011 Accepted in revised form 11 November 2011 Key words: Saurichthys, East Greenland, Wordie Creek Formation, stratigraphy. Published online 2 December 2011 I. Kogan [[email protected]], Freiberg University of Mining and Technology, Geological Institute, Bernhard- von-Cotta str. 2, 09599 Freiberg, Germany.

Numerous fossil fishes from the Early Triassic of East Material and methods Greenland have been collected in the course of several Danish palaeontological expeditions in the 1930s. First The three specimens described below have been col- remains of Saurichthys Agassiz, 1834 were discovered lected by E. Nielsen during the 1930s in the Kap Stosch by Eigil Nielsen in 1932 and only briefly mentioned in area at the north coast of Hold with Hope, East Green- his subsequent publications (Nielsen 1935, 1936, 1961). land (Fig. 1). Nielsen (1935) distinguished six subsequent The fourteen specimens reported in Nielsen (1961) are vertebrate-bearing levels, i.e. five “fish zones” and one stored in The Natural History Museum of Denmark, “tetrapod zone”, in his study area. Of the 14 Saurichthys Copenhagen (Geological Museum – MGUH numbers) specimens enumerated in Nielsen (1961), five were and have never been described in detail, except for referred to his fish zone 2 and nine to his fish zone 5. two skulls (MGUH-VP-992 and -994) that were pub- According to the labels, specimens MGUH-VP-1000 and lished by Mutter et al. (2008) who referred to them as -997 were found in 1933 at the so-called Østlokaliteten Saurichthys cf. ornatus. and Vestlokaliteten, respectively. These localities are Already Nielsen (1936) suggested the possible mentioned in Nielsen (1935: fig. 19) and belong to his fish presence of more than one saurichthyid species in his zone 2 (Nielsen 1935: 100 ff.). Both localities are situated collection because of differences in size and propor- in the Neviatiakdal area and placed in the former Otocer- tions. A preliminary survey of the material indicates as beds. This level corresponds to the interval from that the occurrence of different morphotypes prob- Hypophiceras martini to Metophiceras subdemissum zone ably corresponds to two distinct stratigraphic levels. (lowermost upper Griesbachian) in the stratigraphic At least the specimens MGUH-VP-988, -997 and -1000 scheme of Bjerager et al. (2006) and occurs near the base are referable to a single morphotype based on their of the Wordie Creek Formation only few metres above peculiar squamation. They are described in the fol- the presumed Permian-Triassic boundary. No detailed lowing account. information is given on the specimen MGUH-VP-988.

Remains of Saurichthys (Pisces, Actinopterygii) from the Early Triassic Wordie Creek Formation · 93 All specimens are preserved as concretions in laminated Systematic palaeontology mudstones deposited under marine conditions during a period of local sea-level rise (Bjerager et al. 2006). Subclass: Actinopterygii Cope, 1887 The fossils were studied under a WILD binocular Order: Saurichthyiformes Aldinger, 1937 microscope and photographed with a NIKON D 80 Family: Saurichthyidae Owen, 1860 digital camera with a 35-70 mm zoom lens. Drawings [sensu Stensiö 1925] were made by means of a camera lucida as well as on Genus: Saurichthys Agassiz, 1834 the basis of photographs. To enhance contrasts, speci- Type species: Saurichthys apicalis Agassiz, 1834 men MGUH-VP-988 B was examined and photographed immersed in alcohol. Saurichthys aff. dayi (Raymond, 1925) The use of open nomenclature follows Bengston (1988). Referred material: MGUH-VP-1000 (anterior trunk portion and incomplete skull), MGUH-VP-997 (trunk fragment), MGUH-VP-988 A, B (trunk fragment with dorsal and anal fins in part and counterpart); possibly also MGUH-VP-990 (fragmentary skull) and MGUH- VP-996 (caudal peduncle).

Description Specimen MGUH-VP-1000 (Fig. 2) is an incomplete skull with the anterior body portion preserved in a concretion. Most dermal bones of the skull are weath- ered away and only the right mandible and the right opercular are preserved in lateral view. The preserved portion of the mandible is 124 mm long and the tip of the snout is missing. Delicate subvertical striae can be recognized on the dentary. Some teeth are preserved on both jaws, the largest of them being ca. 4 mm high by 2.5 mm wide. The opercular is considerably higher than long (28 mm high, 17 mm long) and ornamented with con- centric ridges of ganoin parallel to its margins. The cleithrum has the shape of an inverted ‘T’ whose anterior and posterior branches are nearly equal in length. The pectoral fin is fan-shaped and consists of at least 18 unsegmented lepidotrichia. The postcranial body fragment shows 18 mid-lateral scales. They are very high (ca. 25 mm in height to 5 mm in length along the lateral line) and roughly rectangular in shape, and the lateral line sensory canal divides them into a somewhat smaller upper (dorsal) part and a larger lower (ventral) part. The scales are inclined anteroventrally and ornamented with a combination of ridges and tubercles of ganoin. In the lower parts, subvertical and somewhat sigmoidal ridges predominate and tubercles are restricted to the margins of the scale. The pattern is similar in the upper parts of the anteriormost scales, whereas farther back the ornament is composed of tubercles arranged Fig. 1. Map of East Greenland showing the outcrop areas of the in subhorizontal rows. Early Triassic Wordie Creek Formation and the assumed find Further scales are present on the body but neither locality of Saurichthys aff. dayi on the north coast of Hold With their number nor their exact shape can be determined Hope. Modified from Bjerager et al. (2006). due to the preservation. It seems, however, that the

94 · Bulletin of the Geological Society of Denmark anterior scales of the mid-dorsal row are oval and very mid-lateral scales. The ornamentation is composed of small, increasing in size posteriorly. tubercles arranged in longitudinal rows. Specimen MGUH-VP-997 (Fig. 3) represents a cast The portion dorsally to the mid-lateral scales is in- of a body fragment presumably between the skull and sufficiently preserved. Several scales of different size the pelvic fins. Remnants of 8 mid-lateral scales are are present, which could possibly reflect the pattern visible. They show the same proportions as described in the ventral part. for specimen MGUH-VP-1000, but it can be seen that Specimen MGUH-VP-988 A and B (Fig. 4) repre- the sigmoidal subvertical ridges that constitute the sents the region of the dorsal and anal fin in part and ornamentation of their lower parts are mainly com- counterpart. About 20 mid-lateral scales are preserved posed of fused tubercles. The upper parts of the scales anteriorly to the fins; compared to the mid-lateral are ornamented with distinct tubercles arranged in scales of more anterior body segments, documented curved, subhorizontal rows. by specimens MGUH-VP-1000 and -997 (apparently Three rows of scales can be distinguished between belonging to individuals of comparable size) they are the mid-lateral and the mid-ventral scale row. The less high (about 20 mm) and slightly more rhombic scales correspond to the mid-lateral scales in number. than rectangular in outline. Their length, however, The long axis of all of these ventrolateral scales is is still between 4 and 5 mm, and the ornamentation anteroventrally directed, opposing the anterodorsal follows the pattern described above. Comparatively axis of the mid-lateral scales. Scales of the uppermost larger areas of the lower part of the scales, near their ventrolateral row are bigger and rectangular in shape anterior and ventral margins, are covered with tu- (ca. 8 to 4 mm), the remaining scales are 3-5 mm long bercles. The scales of the mid-dorsal and mid-ventral and oval to triangular. All of them are ornamented rows are only half as numerous as the mid-lateral ones; with tubercles. further scale rows seem not to be present. The mid-ventral scales are preserved only as im- Scales of the mid-ventral and mid-dorsal rows have pressions of their outside. They are cordiform to V- the same shape in front of the dorsal and anal fins. shaped, pointing posteriorly, 5 mm wide and 7 mm They are rounded, 10-11 mm broad and 11-12 mm long. long. They also roughly correspond in number to the On the inside, a prominent longitudinal keel runs

Fig. 2. Saurichthys aff. dayi, incomplete skull and anterior body portion. Specimen MGUH-VP-1000.

Remains of Saurichthys (Pisces, Actinopterygii) from the Early Triassic Wordie Creek Formation · 95 along the midline, passing from one scale to another. narrow caudal peduncle. Remnants of smaller scales The anterior edge of every scale is pointed and fits into should belong to the mid-lateral row which would a groove on the inside of the preceding one. The sur- have decreased in height in the caudal part. face of the scales presents a V-shaped outline and an Part of the vertebral column is exposed in specimen ornament of tubercles arranged in longitudinal rows. MGUH-VP-988 B (Fig. 4B, C, 5). Ossified dorsal and The dorsal fin is supported by at least 8 endoskeletal ventral elements (pairs of neural and haemal arches, radials divided in elongated proximal axonosts and respectively) are placed dorsolaterally and ventrally square-shaped distal baseosts. The fin consists of at to the notochord, which has partly been calcified. The least 28 lepidotrichia, the longest of which are seg- neural arches consist of an enlarged, rounded basal mented no less than 5 times. Basal and fringing fulcra part narrowing dorsally, and short anterodorsal ar- are present on its anterior margin, whose fragmentary ticulation processes (praezygapophyses). Conspicuous preservation precludes from more exact description posterodorsally ascending neural spines emerge from of these elements. The anal fin is supported by at the neural arches anterior to the dorsal fin. They are least 10 endoskeletal radials, and about 40 segmented cylindrical proximally but become slightly flattened lepidotrichia can be counted, the posteriormost of distally. It is not clear if separate postzygapophyses which are very thin. Three or four basal fulcra can were also developed to articulate with the praezygapo- be recognized in front of it. The anterior margin physes of the following neural arch. The haemal arches bears fringing fulcra. Taking into account that in all are of roughly rectangular shape and are separated known saurichthyids the dorsal and anal fins are from each other by round foramina. They seem to cor- highly symmetrical, the structures of both might be respond to the neural arches in number. Presence of much more similar than they appear due to the state haemal spines is indicated by a couple of elongated ele- of preservation. ments apparently associated with the haemal arches Four mid-ventral and four mid-dorsal scales are (Fig. 4C). The vertebrae are more numerous than the preserved behind the anal and dorsal fin. Their shape mid-lateral scales in the corresponding body portion. is the same as in front of the fins, but both rows are Specimens MGUH-VP-990 and -996 are attributed set closer to each other, forming the beginning of the to the same species only tentatively. MGUH-VP-996

Fig. 3. Saurichthys aff. dayi, fragment probably from the abdominal region as preserved in specimen MGUH- VP-997. Anterior to the left.

96 · Bulletin of the Geological Society of Denmark Fig. 4. Saurichthys aff. dayi, posterior body portion with the opposed dorsal and anal fins. A, specimen MGUH-VP-988 A (anterior to the right); C, its counterpart MGUH-VP-988 B (anterior to the left); B, sketch compiled after both parts (anterior to the right). Abbreviations: af anal fin, df dorsal fin, ao axonosts, bo baseosts, bf basal fulcra, frf fringing fulcra, dsc mid-dorsal scale row, vsc mid-ventral scale row, lsc mid-lateral scales, lsc.l left mid-lateral scale row, lsc.r right mid-lateral scale row, lat.l lateral line, na neural arches, ha haemal arches, not notochord. The box in C indicates the frame of Fig. 5.

Remains of Saurichthys (Pisces, Actinopterygii) from the Early Triassic Wordie Creek Formation · 97 ing localities that, as far as indicated on the labels, correspond to outcrops of fish zone 5 mentioned in Nielsen (1935). This is also the case for MGUH-VP-992 and -994 described by Mutter et al. (2008) as Saurich- thys cf. ornatus. The opercular bone as preserved in specimens MGUH-VP-991 and -992 is posterodorsally expanded, resembling the opercular of Saurichthys ornatus, and the skull fragment MGUH-VP-999 closely resembles MGUH-VP-994 in general shape. Therefore, the specimens MGUH-VP-991, -992, -994 and -999 can preliminarily be referred to Saurichthys cf. ornatus; remaining fossils lack diagnostic features. In summary, the distribution of distinguishable specimens suggests that Saurichthys aff. dayi most probably comes from fish zone 2, whereas Saurichthys cf. ornatus occurs in fish zone 5. Already Nielsen (1935) observed differences in the fossil assemblages of fish zones 2 and 5. For instance, Bobasatrania that by far dominates the assemblage of fish zone 2 is nearly absent in zone 5, which in contrast is dominated by Pteronisculus and parasemionotids (rare in zone 2) and coelacanths (Nielsen, 1961). Ac- cording to the stratigraphic scheme of Bjerager et al. (2006), zone 5 can be placed in the late Griesbachian to possibly early Dienerian, whereas zone 2 is clearly Griesbachian. Whatever the reasons for a faunal change, it is not surprising to find different species of Saurichthys in short stratigraphic succession, as was demonstrated e.g. by Rieppel (1992) for the Monte San Giorgio area. Fig. 5. A, Saurichthys aff. dayi, detail of the vertebral column as preserved in specimen MGUH-VP-988 B; B, interpretative sketch of A. Abbreviations: na neural arch, ha haemal arch, prz praezygapophysis, ns neural spine. Anterior to the left. Position Discussion and conclusions of picture is shown in Fig. 4C. The new Greenland saurichthyid most closely resem- is the fragment of a caudal peduncle, showing a part bles Saurichthys dayi (Raymond, 1925) from the Early of a dorsal or anal fin and several V-shaped scales Triassic (Griesbachian–Smithian or Spathian) of Al- ornamented with tubercles. MGUH-VP-990 is a frag- berta and British Columbia, as described and depicted mentary skull with rather short, rounded opercular, by Mutter et al. (2008). Characteristics of this species resembling that of MGUH-VP-1000. Both specimens are very high, somewhat rhomboidal mid-lateral scales probably also come from Nielsen’s (1935) fish zone 2, and V-shaped to oval, broad mid-dorsal and mid- as suggested by their finding localities: MGUH-VP-996 ventral scales; these are ornamented with longitudinal was collected at Østlokaliteten, and MGUH-VP- 990 at rows of tubercles and have a conspicuous longitudinal River 13 which is also located in the Neviatiakdal area. keel on their inside which takes part in the scale-to- scale articulation within each row (Mutter et al. 2008: fig. 11). This pattern is best seen in the specimen Remarks MGUH-VP-988. The mid-lateral scales also strongly resemble those depicted by Mutter et al. (2008). If the assumption of their provenience is correct, High mid-lateral scales have also been reported by the specimens here referred to Saurichthys aff. dayi Stensiö (1925) for Saurichthys wimani (Woodward, 1912) are the five Saurichthys specimens listed by Nielsen and Saurichthys elongatus Stensiö, 1925 from the Smith- (1961) for fish zone 2. Accordingly, the remaining ian of Spitzbergen, and by Lehman (1952) for the Die nine specimens must be those collected from fish nerian Saurichthys madagascariensis Piveteau, 1944-45. zone 5; indeed, this is in agreement with their find- However, the two aforementioned forms differ from

98 · Bulletin of the Geological Society of Denmark the Greenland material in having small mid-dorsal gratefully acknowledged. Thanks are due to the State and mid-ventral scales (Stensiö 1925). Saurichthys of Saxony for a current PhD fellowship to the author. madagascariensis, in turn, has mid-dorsal and mid- The work in Copenhagen was supported by a grant ventral scales of comparable shape (but ornamented from the European Commission’s (FP 6) Integrated with striae rather than with tubercles), but Rieppel Infrastructure Initiative programme SYNTHESYS (1980) judged the high scales to be the ventro-lateral (DK-TAF). ones, suggesting that the lateral line is supported by a series of smaller, square-shaped to rounded scales. According to Rieppel’s (1980) description, there are no smaller scales between the high lateral scales and the mid-ventral scale row, in contrast to what is seen References in the Greenland material. Agassiz, L. 1834: Abgerissene Bemerkungen über fossile Fische. The existence of additional ventrolateral and/or Neues Jahrbuch für Mineralogie, Geognosie, Geologie und dorsolateral scale rows in Saurichthys dayi could not Petrefaktenkunde 1834, 379–390. be ruled out by Raymond (1925), neither by Schaeffer Aldinger, H. 1937: Permische Ganoidfische aus Ostgrönland. & Mangus (1976) who even questioned the validity of Meddelelser om Grønland 102(3), 1–392. Bengston, P. 1988: Open nomenclature. Palaeontology 31(1), the species, nor by Mutter et al. (2008) who described 223–227. additional material. However, Mutter et al. (2008) re- Bjerager, M., Seidler, L., Stemmerik, L. & Surlyk, F. 2006: Am- ported on anterior flanks entirely covered by scales. monoid stratigraphy and sedimentary evolution across the In the Greenland form, ventrolateral and dorsolateral Permian-Triassic boundary in East Greenland. Geological scales seem to be absent in the region behind the pelvic Magazine 143(5), 635–656. fins, as indicated by the specimen MGUH-VP-988. Cope, E.D. 1887: Geology and Palæontology. Zittel’s manual on Nevertheless, belonging of the present material Palæontology. American Naturalist 22(11), 1014–1019. Lehman, J.-P. 1952: Etude complémentaire des Poissons de to Saurichthys dayi seems improbable because this l’Eotrias de Madagascar. Kungliga Svenska Vetenskapsa- latter species has all fin rays unsegmented (Schaef- kademiens Handlingar Serie 4, vol. 2(6), 1–201. fer & Mangus 1976; Mutter et al. 2008). The strong Mutter, R.J., Cartanyà, J. & Basaraba, S.A.U. 2008: New evidence segmentation of dorsal and anal fin in MGUH-VP-988 of Saurichthys from the Lower Triassic with an evaluation of represents, for the moment, the only diagnostic feature early saurichthyid diversity. In: Arratia, G., Schultze, H.-P., distinguishing the new form from Saurichthys dayi. & Wilson, M.V.H. (eds), Mesozoic Fishes 4 – Homology and It is therefore probable that the material described Phylogeny. Verlag Dr. Friedrich Pfeil, München, 103–127. Nielsen, E. 1935: The Permian and Eotriassic Vertebrate-bearing constitutes a new species of Saurichthys. The incom- Beds at Godthaab Gulf (East Greenland). Meddelelser om pleteness of the specimens and the fact that material Grønland 98(1), 1–111. of Saurichthys dayi could not be examined, however, Nielsen, E. 1936: Some few preliminary Remarks on Triassic prevents from establishing a new taxon. According to Fishes from East Greenland. Meddelelser om Grønland Mutter et al. (2008), further saurichthyid fossils from 112(3), 1–55. Greenland should exist in collections. If so, they have Nielsen, E. 1961: On the Eotriassic Fish Faunas of Central East to be incorporated into a more detailed study, which Greenland. In: Raasch, G.O. (ed.), Geology of the Arctic. Volume 1. Toronto University Press, Toronto, 255–257. should also include the re-investigation of the forms Owen, R. 1860: Palaeontology or A systematic summary of from North America and Spitzbergen. extinct animals and their geological relations. A. and C. Black, Edinburgh, 420 pp. Piveteau, J. 1944–1945: Paléontologie de Madagascar. XXV – Les Poissons du Trias inférieur. La famille des Saurichthyidés. Annales de Paléontologie 31, 79–89. Acknowledgements Raymond, P.E. 1925: Two new fossil fishes from Alberta. Ameri- can Journal of Science Series 5, vol. 10(60), 551–555. The author is grateful to Gilles Cuny and his team Rieppel, O. 1980: Additional specimens of Saurichthys madagas- from MGUH for providing access to the collection, cariensis PIVETEAU, from the Eotrias of Madagascar. Neues technical equipment, literature, maps and field data, Jahrbuch für Geologie und Paläontologie, Monatshefte 1, and to Jörg W. Schneider, Freiberg, and Andrea Tintori, 43–51. Milano, for their encouragement and valuable discus- Rieppel, O. 1992: A new species of the genus Saurichthys (Pi- sions. Helpful suggestions came from Martin Licht sces: Actinopterygii) from the Middle Triassic of Monte San and Jan Fischer, Freiberg, Monette Véran, Paris, and Giorgio (Switzerland), with comments on the phylogenetic interrelationships of the genus. Palaeontographica Abt. A the editors. Comments by the reviewers Cristina Lom- 221, 63–94. bardo, Milano and Adriana López-Arbarello, Munich, Schaeffer, B. & Mangus, M. 1976: An Early Triassic fish as- greatly improved the final version of the manuscript. semblage from British Columbia. Bulletin of the American Linguistic revision by Lee W. Janson, Edinburgh, is Museum of Natural History 156(5), 515–564.

Remains of Saurichthys (Pisces, Actinopterygii) from the Early Triassic Wordie Creek Formation · 99 Stensiö, E.A. 1925: Triassic fishes from Spitzbergen. Kungliga Svenska Vetenskapsakademiens Handlingar Serie 3, vol. 2(1), 1–261. Woodward, A.S. 1912: Notes on some Fish-remains from the Lower Trias of Spitzbergen. Bulletin of the Geological Institu- tion of the University of Uppsala 11, 291–297.

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